The invention relates generally to methods of sizing metal sleeves, and particularly relates to a method of sizing small outside diameter metal sleeves using a magnetic field. These sleeves can be utilized as substrates for imaging members such as layered photoreceptors, reference Stolka et al., U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated by reference.
The process of sizing metal sleeves generally includes expanding the metal sleeve, or at least a portion thereof, to a desired finished size and shape. Several methods of sizing metal sleeves are known in the art. One known method provides for the insertion of a mandrel into the metal sleeve. An inner surface of the metal sleeve is generally coated with a lubricant and the mandrel contacts the inner surface to expand the metal sleeve to a desired size. Another method, known as hydroforming, uses hydraulic pressure to expand the metal sleeve. Fluid is passed through the metal sleeve and contacts the inner surface. The resulting pressure is controlled to expand the metal sleeve to a desired size.
In another known method of metal forming, generally referred to as magnaforming, there is generated a magnetic field to exert pressure on the sleeve. This method generally requires the use of sleeves composed of electrically conductive material. The conductive sleeves are placed in a split die with a magnetic coil. The magnetic coil generates a magnetic field which induces current in the conductive sleeve, thereby creating an opposing magnetic field. The net magnetic force between the two opposing magnetic fields exerts substantial pressure on the sleeve to expand the sleeve against an inner surface of the die. This process is disclosed in U.S. Pat. No. 2,976,907, to Harvey et al., the disclosure of which is totally incorporated herein by reference. In particular, Harvey et al. discloses a metal conductor bent back upon itself in hairpin fashion which is positioned inside the sleeve.
Several applications require the sized metal sleeves to have precise and uniform dimensions, and highly polished outer surfaces. For example, components used in xerographic apparatus, such as photoreceptor substrates, must be uniformly sized and have highly polished outer surfaces to ensure that a toner powder image formed on the photoreceptor substrate is accurately transferred to a copy sheet to clearly depict an image of the original document.
It is believed that the aforementioned methods do not consistently produce sized sleeves having uniform dimensions and highly polished outer surfaces. The hydroforming and mandrel methods, which require physical contact with the inner surface of the sleeve, do not consistently produce sized sleeves having precise and uniform dimensions. Additionally, these methods may also damage the inner surface of the sleeve due to the requirement of physical contact. The method of sizing using a split die and magnetic coil can generally produce sized sleeves having more precise and uniform dimensions than those requiring physical contact with the sleeve. However, magnaforming employing conventional expansion coils, comprised of metal coils wound on an insulating material, is impractical for small diameter tubes, especially those with thin walls, as there is insufficient room to satisfy clearance for cooling and to prevent electrical arcing, i.e., short circuits.
In co-pending Cherian et al., U.S. Ser. No. 07/990,852, filed Dec. 14, 1992, the disclosure of which is totally incorporated by reference, there is disclosed a method of sizing a sleeve of electrically conductive material, the sleeve having inner and outer surfaces, comprising the steps of: inserting the sleeve in a die having an inner surface; positioning a magnetic field generating means inside the sleeve in the die; sealing the die after the insertion of the sleeve and the positioning of the magnetic field generating means; creating a vacuum inside the die to avoid air pockets between the outer surface of the sleeve and the inner surface of the die; and energizing the magnetic field generating means to create a magnetic field to expand the sleeve against the inner surface of the die.
In co-pending Cherian et al., U.S. Ser. No. 08/043,888, filed Apr. 7, 1993, the disclosure of which is totally incorporated by reference, there is disclosed a method for the removal of layered material from a photoreceptor comprising an electrically conductive substrate, wherein the method comprises: employing a magnetic field to expand or shrink the width of at least a portion of the substrate, whereby a portion of the layered material over the expanded or shrunken portion of the substrate becomes loosened from the photoreceptor.